Laser peening extends the lifetime of Rolls-Royce fan blades

To ensure the safe lifetime of Trent engine fan blades, Rolls-Royce adopted a process known as laser shock peening (LSP). It is now used to treat all Trent 500, Trent 800, Trent 1000 and XWB blades. Sales of 1,200 treated Trent XWB engines alone are worth more than £60 billion.

Fan blades in aircraft engines suffer large loads and high frequency vibrations. Over time these stresses can create microscopic cracks in the blades which could eventually cause potentially catastrophic and life threatening engine failure.

The traditional method for stopping cracks is to fire 'shot' at the blades; the shallow indentations create compressive residual stresses that stop cracks growing. But when two Trent 800 blades failed testing, Rolls-Royce decided to explore laser shock peening (LSP), an alternative approach which introduces compressive stresses to a much greater depth via a plasma created by a powerful pulsed laser.

Guaranteed safe lives with LSP

Researchers from the School of Materials analysed the potential of LSP to strengthen blades. Using penetrating synchrotron X-ray beams they discovered that the laser method generates deep compressive stresses which remain stable under the fatigue loading of air travel.

Following our comprehensive evaluation of the safety and benefits of LSP-treated blades, Rolls-Royce’s adopted LSP to treat its Trent 800 engine. Since then, the company has applied LSP to Trent 500, Trent 800, Trent 1000 and XWB engines. So far, Rolls-Royce has sold more than 1,200 of its latest XWB engines – worth over £60 billion in total.

LSP treatment is contracted by Rolls-Royce to Curtiss-Wright Surface Technologies (formerly The Metal Improvement Company) which has received training and expert support from our research team. Curtiss-Wright runs a dedicated facility near to Rolls-Royce’s blade production centre, employing 30 people. Curtiss-Wright recently won a contract to set up a similar facility inside Rolls-Royce’s Singapore plant, which will produce a further 6,000 blades annually.

Materials Testing and Analysis Unit

Blades

6,000 blades manufactured in Rolls-Royce's Singapore plant annually.

As part of our partnership with Rolls-Royce, we established a Materials Testing and Analysis Unit to routinely test LSP-treated fan blade components using X-ray diffraction residual stress measurement. Today the Unit confirms the integrity of the LSP-based manufacturing process each and every month; this work is integral to Rolls-Royce’s quality assurance and contributes to Civil Aviation Authority accreditation of Trent aero-engines.

The MTA Unit generates a turnover of £100,000 from Rolls-Royce alone.

Background

Orders

£60 billion orders for Rolls-Royce LSP-treated Trent XWB engines.

Revenue

£8.6 billion annual revenue for Rolls-Royce's aeroengine business.

Researchers in the School of Materials, led by Professor Philip Withers, have studied the fundamental nature of LSP-induced compressive residual stress. They found that LSP is preferable to more established shallow peening for fan blades' roots which experience contact fatigue.